1. Field of the Invention
The present invention relates to load transfer trailers for carrying a portion of the load on a truck, such as a transit mixer.
2. Prior Art
In the prior art various forms of trailers or auxiliary axle assemblies have been utilized at the rear of frames on large trucks. For example, U.S. Pat. No. 3,112,100 shows such a frame assembly which has a hopper that is attached thereto and which can be used for loading material into the mixer itself.
Additionally, a device for carrying a portion of the load through an auxiliary axle that can be selectively engaged with the ground is shown for example in U.S. Pat. No. 3,161,418. U.S. Pat. No. 3,191,961 illustrates a tag axle assembly that can be raised from a working position up into a storage position, and this patent includes an accumulator so that the amount of load being carried on the rear axle is limited by the pressure in the accumulator.
Jointed arms for holding a rear axle assembly are shown in U.S. Pat. No. 3,246,884 and this device includes latches which hold the unit in a locked position. Air bags that are used for actuating auxiliary axles are shown in U.S. Pat. No. 3,704,896. A separate hydraulic cylinder is used in this particular patent for lifting the tag axle when the pressure in the air bags is released. Air bellows also are used directly at the axle in U.S. Pat. No. 3,912,293, which has a jointed arm assembly that folds to place the wheels close to the ground when the assembly is folded.